Surgical fastener applying aparatus

ABSTRACT

A surgical fastener applying apparatus for applying fasteners to body tissue including a cartridge receiving half-section defining an elongated channel member configured to releasably receive a stationary housing of a firing assembly. The stationary housing is dimensioned to releasably receive a single use loading unit therein, and includes a lockout structure that prevents insertion of the stationary housing into the cartridge receiving half-section if the single use loading unit is not mounted in the stationary housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 13/546,956 filed Jul. 11, 2012, which claims benefit of and priority to U.S. Provisional Application No. 61/521,078 filed Aug. 8, 2011, and the disclosures of each of the above-identified applications are hereby incorporated by reference in their entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a surgical fastener applying apparatus and, more particularly, to a surgical fastener applying apparatus having reusable and disposable components.

2. Discussion of Related Art

Surgical fastener applying apparatus, wherein tissue is first grasped or clamped between opposing jaw structures and then joined by means of surgical fasteners, are well known in the art. In some such apparatus, a knife is provided to cut the tissue which has been joined by the fasteners. The fasteners are typically in the form of surgical staples, although, other surgical fasteners may also be utilized, such as, for example, clips or two part polymeric surgical fasteners.

Surgical fastener applying apparatus typically include two elongated beam members which are used to capture or clamp tissue therebetween. Typically, one of the beam members carries a disposable cartridge assembly which houses a plurality of staples arranged in at least two lateral rows, while the other beam member includes an anvil which defines a surface for forming the staple legs as the staples are driven from the cartridge assembly. Where two part fasteners are used, the beam member which includes the anvil carries a mating part of the two part fastener, e.g. the receiver. Generally, the staple formation process is affected by the interaction between one or more longitudinally moving camming members and a series of individual staple pushers. As the camming members travel longitudinally through the cartridge carrying beam member, the individual pusher members are biased upwardly into a backspan of the staples supported within the cartridge assembly to sequentially eject the staples from the cartridge. A knife may be provided to travel with the camming members between the staple rows to cut the tissue between the rows of formed staples. An example of such an instrument is disclosed in U.S. Pat. No. 7,631,794, which is incorporated herein in its entirety by reference.

Because of the dangers associated with improper sterilization, fastener applying apparatus are typically disposable after use. Although the cartridge assembly may be replaced to perform multiple fastener applying operations on a single patient, the staple applying apparatus is typically disposable after a surgical procedure has been completed. This requirement of disposability may increase the costs associated with surgical procedures. Although reusable fastener applying apparatus have been developed, such apparatus can be overly complex and prove difficult to sterilize.

A need exists in the art for a fastener applying apparatus which includes reusable components, is not overly complex and is configured to facilitate proper sterilization after use in a surgical procedure.

SUMMARY

The present disclosure relates to surgical fastener applying apparatus for applying surgical fasteners to tissue. The surgical fastener applying apparatus in one aspect comprises an anvil half-section including a distal anvil portion, a cartridge receiving half-section defining an elongated channel member, and a stationary housing. The stationary housing is configured to be releasably supported within the elongated channel member of the cartridge receiving half-section. The stationary housing supports firing components of the apparatus. The stationary housing is also dimensioned to releasably receive a single use loading unit. A lockout structure prevents full insertion of the stationary housing into the cartridge receiving half-section if the single use loading unit is not mounted in the stationary housing.

In some embodiments, the lockout structure may define a first position which prevents insertion of the stationary housing into the cartridge receiving half-section and a second position which permits insertion of the stationary housing into the cartridge receiving half-section.

In some embodiments, the lockout structure includes a flexible member movable from the first position to the second position in response to insertion of the single use loading unit into the stationary housing. In one embodiment, the flexible member includes a protrusion extending beyond a bottom surface of the stationary housing and the cartridge receiving half-section defines a groove therein to receive the protrusion of the flexible member. Thus, in this embodiment, when the flexible member is in the first position, the protrusion of the flexible member is misaligned with respect to the groove of the cartridge receiving half-section and when the flexible member is in the second position, the protrusion of the flexible member is aligned with respect to the groove of the cartridge receiving half-section and readily insertable into the groove.

In another embodiment, the flexible member defines a recess configured to receive a top edge of a sidewall of the cartridge receiving half-section therein when the flexible member is in the second position. In this embodiment, when the flexible member is in the first position, the recess defined by the flexible member is misaligned with respect to the top edge of the cartridge receiving half-section, and when the flexible member is in the second position, the recess defined by the flexible member is aligned with respect to the top edge of the cartridge receiving half-section and is configured to readily receive the top edge of the cartridge receiving half-section.

In another aspect, the present disclosure provides a surgical fastener applying apparatus comprising a reusable anvil half-section, a reusable cartridge receiving half-section, and a disposable firing assembly configured to be releasably supported within the cartridge receiving half section. The firing assembly includes a disposable pusher assembly and a disposable single use loading unit mountable to the pusher assembly, wherein the firing assembly is fully insertable into the cartridge receiving half section for actuation of the apparatus only if the firing assembly contains the single use loading unit.

The apparatus may further include a blocking member movable between a first position which prevents full insertion of the firing assembly into the cartridge receiving half-section and a second position which permits full insertion of the firing assembly into the cartridge receiving half-section.

In some embodiments, the blocking member is a flexible member extending from a wall of a housing of the pusher assembly and biased to the first position, and the single use loading unit applies a force to the flexible member to move the flexible member to the second position when mounted to the firing assembly to enable full insertion of the firing assembly.

In some embodiments, the flexible member includes a protrusion extending beyond a bottom surface of a housing of the pusher assembly to contact a surface of the cartridge receiving half section, and the cartridge receiving half-section defines a groove therein to receive the protrusion of the flexible member when the single use loading unit is mounted to the pusher assembly, the protrusion of the flexible member being misaligned with respect to the groove of the cartridge receiving half-section when the single use loading unit is not mounted to the pusher assembly. In other embodiments, the flexible member includes a hook defining a recess, the recess configured to receive a top edge of a sidewall of the cartridge receiving half-section therein when the flexible member is in the second position and configured to abut the top edge when the flexible member is in the first position.

In another aspect, the present disclosure provides a disposable firing assembly for use with a surgical fastener applying apparatus comprising a disposable single use loading unit and a disposable pusher assembly. The firing assembly is insertable into a cartridge receiving half section of the fastener applying apparatus and the single use loading unit is operably mountable to the pusher assembly, wherein the firing assembly includes a lockout member movable from a first blocking position preventing operable insertion of the firing assembly into the fastener applying apparatus and a second unblocking position to enable full operable insertion of the firing assembly into the fastener applying apparatus.

In some embodiments, the lockout member is biased to the first position, and the single use loading unit when mounted to the pusher assembly applies a force to the lockout member to move it to the second position.

In some embodiments, the lockout member includes a protrusion enagable with a groove in the fastener applying apparatus when in the second position, the protrusion being misaligned with respect to the groove in the first position of the lockout member. In other embodiments, the lockout member includes a recess configured to receive a top edge of a sidewall of a cartridge receiving half-section of the fastener applying apparatus when the lockout member is in the second position and configured to abut the top edge when the lockout member is in the first position.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed surgical fastener applying apparatus will now be described herein with reference to the accompanying figures wherein:

FIG. 1 is a side perspective view from the distal end of one embodiment of the presently disclosed surgical fastener applying apparatus in the clamped position;

FIG. 2 is a side perspective view from the proximal end of the surgical fastener applying apparatus shown in FIG. 1 in the clamped position;

FIG. 2A is a side perspective view of the surgical fastener applying apparatus shown in FIG. 1 in the open position;

FIG. 2B is an enlarged view of the indicated areas of detail shown in FIG. 2A;

FIG. 3 is a side perspective view with parts separated of the surgical fastener applying apparatus shown in FIG. 1;

FIG. 3A is a side cross-sectional view of the clamp lever of the fastener applying apparatus shown in FIG. 1;

FIG. 4 is a side perspective view of the cartridge receiving half-section of the surgical fastener applying apparatus shown in FIG. 1 with the single use loading unit and the firing assembly supported within the cartridge receiving half-section;

FIG. 5 is an enlarged view of the indicated area of detail shown in FIG. 4;

FIG. 6 is a perspective view from above of the cartridge receiving half-section of the surgical fastener applying apparatus with the SULU and the firing assembly supported therein;

FIG. 7 is an enlarged view of the indicated area of detail shown in FIG. 6;

FIG. 8 is a front end perspective view from above of the firing assembly of the surgical fastener applying apparatus shown in FIG. 3;

FIG. 9 is an enlarged view of the indicated area of detail shown in FIG. 8;

FIG. 9A is a top, perspective view of the channel member with the firing assembly releasably secured therein;

FIG. 9B is an enlarged view of the indicated area of detail shown in FIG. 9A;

FIG. 9C is a top, perspective view of a central portion of the channel member;

FIG. 10 is a rear end perspective view from above of the firing assembly shown in FIG. 8;

FIG. 11 is an enlarged view of the indicated area of detail shown in FIG. 10;

FIG. 12 is a side perspective view of the firing assembly shown in FIG. 10 with parts separated;

FIG. 12A is a bottom perspective view of the cam bar of the firing assembly shown in FIG. 12;

FIG. 12B is a bottom perspective view of the firing lever of the firing assembly shown in FIG. 12;

FIG. 13 is a side perspective view of the SULU of the surgical fastener applying apparatus shown in FIG. 1;

FIG. 14 is an enlarged view of the indicated area of detail shown in FIG. 13;

FIG. 15 is a front perspective view of the SULU shown in FIG. 13;

FIG. 16 is an enlarged view of the indicated area of detail shown in FIG. 15;

FIG. 17 is a side perspective view with parts separated of the SULU shown in FIG. 15;

FIG. 18 is a side cross-sectional view of the surgical fastener applying apparatus shown in FIG. 1 in the open position;

FIG. 19 is an enlarged view of the indicated area of detail shown in FIG. 18;

FIG. 20 is an enlarged view of the indicated area of detail shown in FIG. 18;

FIG. 21 is a perspective view of the proximal end of the surgical fastener applying apparatus shown in FIG. 18 in the open position;

FIG. 22 is an enlarged view of the indicated area of detail shown in FIG. 18;

FIG. 23 is a perspective view from below the proximal end of the clamping lever of the surgical fastener applying apparatus shown in FIG. 1;

FIG. 24 is a side perspective view of the surgical fastener applying apparatus shown in FIG. 1 in the clamped position;

FIG. 25 is a side cross-sectional view of the surgical fastener applying apparatus shown in FIG. 24 in the clamped position;

FIG. 26 is an enlarged view of the indicated area of detail shown in FIG. 25;

FIG. 27 is an enlarged view of the indicated area of detail shown in FIG. 25;

FIG. 28 is a cross-sectional view taken along section lines 28-28 of FIG. 26;

FIG. 29 is a top view of the surgical fastener applying apparatus shown in FIG. 1 as the firing assembly is moved through an actuating stroke to eject fasteners from the fastener applying apparatus;

FIG. 30 is a side cross-sectional view of the surgical fastener applying apparatus shown in FIG. 29 with the firing assembly in the actuated position;

FIG. 31 is an enlarged view of the indicated area of detail shown in FIG. 30;

FIG. 32 is an enlarged view of the indicated are of detail shown in FIG. 30;

FIG. 33 is a side cross-sectional view of the surgical fastener applying apparatus shown in FIG. 1 after the apparatus has been fired and moved to the open position;

FIG. 34 is an enlarged view of the indicated area of detail shown in FIG. 33;

FIG. 35 is a perspective view of an alternate embodiment of the stationary housing of the firing assembly;

FIG. 35A is an enlarged view of the indicated area of detail shown in FIG. 35;

FIG. 36 is a schematic view of an alternate embodiment of the cartridge receiving half-section for receiving the stationary housing of FIG. 35;

FIG. 36A is an enlarged view of the indicated area of detail shown in FIG. 36;

FIG. 37 is a perspective view of another alternate embodiment of the stationary housing of the firing assembly;

FIG. 37A is a side cross-sectional view of the stationary housing of FIG. 37 not fully received in the cartridge receiving half-section; and

FIG. 37B is a side cross-sectional view of the stationary housing of FIG. 37 fully received in the cartridge receiving half-section.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the presently disclosed surgical fastener applying apparatus in accordance with the present disclosure will now be described in detail with reference to the drawings wherein like reference numerals identify similar or identical structural elements. As used herein, as is traditional, the term “proximal” refers to the end of the apparatus which is closer to the user and the term distal refers to the end of the apparatus which is further away from the user.

FIGS. 1-34 illustrate one embodiment of the presently disclosed surgical fastener applying apparatus designated generally as surgical stapler 10. Referring specifically to FIGS. 1-3, surgical stapler 10 includes an anvil half-section 12, a cartridge receiving half-section 14, a clamping lever 16, a single use loading unit 18 (hereinafter “SULU”) and a firing assembly 20. In one embodiment, anvil half-section 12, cartridge receiving half-section 14 and clamping lever 16 are constructed to be reusable components and, as such, are constructed from a biocompatible material suitable for sterilization and repeated use, e.g., stainless steel. In contrast, SULU 18 and firing assembly 20 are constructed to be disposable and, as such, may be constructed from any suitable biocompatible material, e.g., plastics, metals, combinations thereof, having the requisite strength characteristics.

Referring to FIGS. 3-7, cartridge receiving half-section 14 defines an elongated channel member 22 which defines a substantially U-shaped channel 24 having a distal portion 24 a dimensioned to releasably receive a SULU 18 and a proximal portion 24 b dimensioned to releasably receive firing assembly 20. Firing assembly 20 includes a stationary housing 26 (see also FIG. 12) having a proximal end including openings 28 which receive ends of pivot members 29 (FIG. 12). Pivot members 29 pivotally support a locking member 206 on a proximal end of stationary housing 26 and extend through openings 28 into recesses 30 formed in a proximal portion of cartridge receiving half-section 14 to releasably secure the proximal end of firing assembly 20 within the proximal portion 24 b of channel member 22 as will be discussed in further detail below. The distal end of firing assembly 20 defines a triangular cutout 64 d. Cutout 64 d is positioned to receive a protrusion 65 formed on an inner wall of channel member 22 (see FIGS. 9A-9C) to releasably secure the distal end of firing assembly 20 within channel member 22. The structure of firing assembly 20 will also be discussed in further detail below. Likewise, SULU 18 includes a pair of distal protrusions 32 which are positioned in cutouts 34 formed at the distal end of channel member 22 to releasably secure SULU 18 within the distal portion 24 a of channel member 22. During assembly, firing assembly 20 must be inserted into proximal portion 24 b of channel member 22 before SULU 18 is inserted into distal portion 24 a of channel member 22 as will be discussed below. To position SULU 18 in channel member 22, protrusions 32 on SULU 18 are positioned within cutouts 34 while SULU 18 is positioned above and at an angle to channel member 22. Thereafter, SULU 18 can be rotated downwardly into distal portion 24 a of U-shaped channel 24. This allows for the drive components of firing assembly 20 to properly align with components of SULU 18 and also facilitates engagement of the firing assembly 20 with a knife 40 (FIG. 17) supported within SULU 18. A proximal end of SULU 18 includes an outwardly extending serrated surface 42 (FIG. 7) to facilitate gripping of the proximal end of SULU 18 to allow for removal and/or replacement of SULU 18 from channel member 22. Prior to movement of stapler 10 to the clamped position, as will be discussed below, serrated gripping surface 42 will not fully seat within distal portion 24 a of channel member 22.

Referring to FIGS. 8-12, firing assembly 20 includes stationary housing 26, a knife actuating bar 44, a cam bar 46, a guide block 48, a firing lever 50, a slide block 52, a pedal 54 and the pivotal locking member 206 (FIG. 12). In one embodiment, stationary housing 26 includes a U-shaped frame 60 including a bottom wall 62 and a pair of sidewalls 64. The distal end of each sidewall 64 defines a proximal step 64 b, a distal angled portion 64 c (FIG. 9) and the triangular cutout 64 d. As discussed above, triangular cutout 64 d is positioned to receive the protrusion 65 (FIG. 9B) formed on an inner wall of channel member 22. A proximal end of each sidewall 64 includes a pair of transversely extending deformable wall portions 66 (FIG. 11) which are spaced from a proximal end of slide block 52 and define an area between wall portions 66 and slide block 52 for pivotally receiving locking member 206 as will be discussed in further detail below.

Guide block 48 includes a body defining three longitudinal slots 70 a-c and a pair of outwardly extending protrusions 72. In one embodiment, each protrusion 72 is substantially cylindrical and includes a tapered portion 72 a (FIG. 9). Alternately, other protrusion configurations are envisioned. Protrusions 72 are dimensioned to be received in openings 74 (FIG. 12) formed in sidewalls 64 of stationary housing 26 to axially fix guide block 48 within the distal end of stationary housing 26. Protrusions 72 allow for a degree of pivotal movement of guide block 48 within U-shaped frame 60. As will be discussed in further detail below, guide block 48 is pivotal from a first position (FIG. 19) in locking engagement with notches 49 and 51 of knife actuating bar 44 to a second position (FIG. 26) disengaged from notches 49 and 51 of knife actuating bar 44 in response to movement of stapler 10 to the clamped position. A torsion spring is provided about protrusion 72 to urge guide block 48 into locking engagement with notches 49 and 51. Each of slots 70 a and 70 c is dimensioned to slidably receive a respective sidewall 114 of cam bar 46. Similarly, slot 70 b is dimensioned to slidably receive knife actuating bar 44.

Slide block 52 includes a hub 80 which includes a resilient finger 80 a configured to be snap-fit into a pivot hole 82 formed in firing lever 50. Firing lever 50 is pivotal about hub 80 when the slide block 52 is in a retracted position to facilitate actuation of the firing assembly 20 from either side of stapler 10. Pedal 54 is reciprocally received within a hole 84 formed in slide block 52. Pedal 54 includes a split body portion 54 a which is configured to straddle a proximal end 102 of knife actuating bar 44. In one embodiment, split body portion 54 a includes an angled distal surface 86. A pin 88 extends upwardly from pedal 54 through hole 84 in slide block 52. A biasing member 90 is positioned between split body portion 54 a and slide block 52, about pin 88 to urge pedal 54 downwardly away from slide block 52 to an extended position. In the retracted position of slide block 52, pedal 54 is received in a cutout 55 formed in a bottom wall 22 a of channel member 22 (FIG. 20).

Firing lever 50 includes first and second finger engagement members 50 a and 50 b, either one of which can be selectively engaged to move the firing lever 50 through a firing stroke from either side of stapler 10. An arcuate recess 94 (FIG. 12B) is formed in a bottom surface of firing lever 50 which slidably receives pin 88 of pedal 54 to define the range of rotation through which firing lever 50 can pivot about hub 80 of slide block 52. As used herein, a firing stroke is defined as movement of firing lever 50 from a fully retracted position (FIG. 25) to a fully advanced position (FIG. 30). A stop recess 94 a is formed at each end of arcuate recess 94. Stop recesses 94 a are configured and dimensioned to receive the end of pin 88 of pedal 54 to prevent pivotal movement of firing lever 50 about hub 80 during a firing stroke of surgical stapler 10. More specifically, when the firing assembly 20 is actuated to advance slide block 52 distally within stationary housing 26, angled distal surface 86 of pedal 54 engages channel member 22 and is cammed out of cutout 55 (FIG. 27) to urge pin 88 upwardly into a stop recess 94 a to prevent pivotal movement of firing lever 50 during movement of firing lever 50 through a firing stroke. As is evident, pin 88 must be positioned beneath a stop recess 94 a to allow pedal 54 to lift upwardly from cutout 55 to allow firing lever 50 to be moved through the firing stroke. Thus, firing lever 50 must be pivoted to one side or the other of firing assembly 20 before the firing lever 50 can be moved through a firing stroke.

Knife actuating bar 44 includes a proximal end having a stepped portion 100 which includes a proximal first step 102 having a first height and a second step 104 having a second height which is greater than the first height. A distal end of actuating bar 44 includes an upturned hook portion 106 and upper and lower notches 49 and 51. A finger 108 projects upwardly from knife actuating bar 44 between first and second steps 102 and 104. As shown in FIG. 27, finger 108 is slidably received within a recess 110 formed in an underside of slide block 52. When slide block 52 is advanced distally within stationary housing 26, finger 108 moves within recess 110 such that slide block 52 moves in relation to knife actuating bar 44 until finger 108 engages a wall 112 (FIG. 32) defining a proximal end of recess 110. When finger 108 engages wall 112, further distal movement of slide block 52 will also effect distal movement of knife actuating bar 44. As will be evident below, this arrangement allows for staples to be ejected from SULU 18 prior to cutting of tissue.

Referring to FIGS. 12 and 12A, cam bar 46 includes a pair of sidewalls 114 and a base wall 116 (FIG. 12A). The proximal end 114 a of each sidewall 114 includes a raised wall portion 118. Each raised wall portion 118 is configured to be fixedly received in a slot (not shown) formed in an underside of slide block 52 to fixedly secure the proximal end of cam bar 46 to slide block 52. Alternately, slide block 52 may be molded about the proximal end of knife actuating bar 44. The distal end of each sidewall 114 includes an angled camming surface 114 b. Base wall 116 defines a distally extending elongated slot 123 (FIG. 12A) which extends from the distal end of cam bar 46 along a substantial length of the cam bar 46 and a proximally extending longitudinal slot 121. Slot 121 is positioned to facilitate the passage of pedal 54 through cutout 55 of channel member 22 when slide block 52 is in the retracted position. See FIG. 27.

Sidewalls 114 of cam bar 46 are slidably positioned in slots 70 a and 70 c of guide block 48 and knife actuating bar 44 is slidably positioned in longitudinal slot 70 b of guide block 48. When firing assembly 20 is supported in channel member 22 and firing lever 50 is pivoted to one side of stationary housing 26 and pushed distally, slide block 52 is moved distally within stationary housing 26. As slide block 52 begins to move distally, tapered surface 86 of pedal 54 engages a proximal edge of channel member 22 defining cutout 55 to urge pedal 54 upwardly out of cutout 55, through slot 121 of cam bar 46, and onto an inner surface of stationary housing 26 of firing assembly 20 (FIG. 27). As this occurs, pin 88 of pedal 54 moves into a stop recess 94 a to prevent further pivotal movement of firing lever 50. If firing lever 50 is not pivoted to a position in which pin 88 is positioned beneath a stop recess 94 a, pedal 54 will be prevented from moving upwardly out of cutout 55 and firing lever 50 will be prevented from moving through a firing stroke. As firing lever 50 is moved distally, finger 108 moves within recess 110 such that knife actuating bar 44 remains stationary as cam bar 46 is advanced distally. When finger 108 engages proximal wall 112 defining recess 110, knife actuating bar 44 is moved distally with slide block 52 and cam bar 46. As will be discussed below, when cam bar 46 and knife actuating bar 44 are moved distally within stationary housing 26 of firing assembly 20 and channel member 22, angled camming surfaces 114 b of cam bar 46 are moved through SULU 18 to eject fasteners from SULU 18. Simultaneously, although with a preset delay equal to the length of recess 110 (FIG. 32), knife actuating bar 44 drives a knife blade 40 through SULU 18 to dissect tissue.

U.S. Pat. No. 7,631,794 (“the '794 patent”) discloses a surgical fastener applying apparatus which includes a firing assembly similar to that described above. The '794 patent is incorporated herein by reference in its entirety.

FIGS. 13-17 illustrate SULU 18. Referring to FIG. 17, SULU 18 includes a body 120, a plurality of staple pushers 122 (only one is shown), a bottom cover 124, a knife 40 having an angled sharpened leading edge or blade 40 a, a plurality of staples 126 (only one is shown), and a pivotally mounted safety lockout 128. A proximal end of body 120 includes a flexible finger 120 a which projects slightly beyond the outer wall defining body 120. Finger 120 a frictionally engages an inner wall of channel member 22 to retain the proximal end of SULU 18 within channel member 22 when SULU 18 is releasably positioned within channel member 22. As is known in the art, body 120 has a plurality of rows of staple retaining slots 130, e.g., four, six, etc. and a linear slotted knife track 132 centrally disposed in body 120. Surgical stapler 10 can be dimensioned to receive or accommodate SULU's of different staple line lengths including, e.g., 60 mm, 80 mm and 100 mm. Knife 40 includes a downturned hook portion 40 b which is positioned to engage upturned hook portion 106 (FIG. 12) of knife actuating bar 44 when SULU 18 is positioned within channel member 22.

In the illustrated embodiment, body 120 includes two staggered rows of slots 130 formed on either side of linear slotted knife track 132. The staggered rows of slots 130 extend beyond the distal end of knife track 132 to facilitate staple formation beyond the distal end of the stroke of the knife blade 40.

Staple pushers 122 may be configured to extend into one or more slots 130. In one embodiment, a single pusher is associated with each slot 130. Alternately, as illustrated in FIG. 17, each pusher 122 can be configured to extend into two adjacent slots 130 and is positioned beneath respective staples 126 which are retained in slots 130. As is known in the art, each pusher 122 includes a lower cam surface 122 a which is positioned to engage one of cam surfaces 114 b (FIG. 12) on the distal end of cam bar 46 such that movement of cam bar 46 through SULU 18 sequentially lifts each respective pusher 122 within its respective slot or slots 130 to eject staples from slots 130.

Bottom cover 124 partially encloses a channel 125 (FIG. 18) formed within the cartridge body 120. A longitudinal ridge 134 is formed on an upper surface of bottom cover 124 and provides a bearing surface for a knife supporting member 136 which is secured to a bottom edge of knife 40. Knife 40 may be secured to supporting member 136 via pins, welding or other known fastening techniques. During a firing stroke, knife 40 is guided along knife track 132 as the firing lever 50 is advanced through channel member 22. A pair of slots 138 is defined between the sides of ridge 134 and an outer wall of cartridge body 120. Longitudinal ridge 134 is positioned within body 120 and dimensioned to be slidably received in elongated slot 120 (FIG. 12A) of cam bar 46 such that cam bar 46 is slidably movable through cartridge body 120 about longitudinal ridge 134 to eject staples 126 from SULU 18.

Safety lockout 128 is pivotally disposed on an upper proximal end of body 120 and is pivotal about a pivot member 150 from a locked orientation (FIG. 26) to unlocked orientation (FIG. 34). Pivot member 150 is received in openings 154 in body 120. A biasing member, e.g., spring 152, is positioned between knife supporting member 136 and safety lockout 128 to urge safety lockout 128 towards the unlocked orientation. Safety lockout 128 includes a proximal hook 156 which is positioned to receive an engagement member 158 formed on the knife 40 to retain the safety lockout 128 in the locked orientation when the knife 40 is in the retracted position (FIG. 19). When the knife 40 is moved towards the advanced position during a firing stroke, engagement member 158 is moved away from proximal hook 156 to allow safety lockout 128 to pivot towards the unlocked position in response to the urging of spring 152. It is noted that safety lockout 128 is prevented from pivoting to the unlocked position when the anvil half-section 12 and cartridge receiving half-section 14 are in the clamped position because the top surface 128 a of safety lockout 128 engages an inner surface of anvil half-section 12 to prevent pivoting of safety lockout 128. Safety lockout 128 defines a slot 160 dimensioned to slidably receive the knife 40. In the retracted position of the knife 40, the leading edge 40 a of knife 40 is confined within slot 160 safety lockout 128 to prevent accidental engagement and injury to medical personnel with leading edge 40 a of knife 40.

Referring again to FIGS. 2-3, anvil half-section 12 includes a proximal handle portion 12 a and a distal anvil portion 12 b. Anvil portion 12 b includes a staple deforming portion 198 which, as known in the art, includes a plurality of staple deforming recesses and faces a top surface of SULU 18 when SULU 18 is positioned in the channel member 22. As is also known in the art, the staple deforming portion 198 includes a central longitudinal slot (not shown) for receiving the knife 40 (FIG. 17) as the knife 40 is moved through the SULU 18. The staple deforming portion 198 can be formed integrally with anvil half-section 12, or in the alternative, secured to anvil half-section 12 by a fastening process such as welding. A pair of locating fingers 170 (FIG. 3) are positioned adjacent the proximal end of the staple deforming portion 198 of anvil portion 12 b. Locating fingers 170 are received in grooves in SULU 18 to properly align SULU 18 with staple determining portion 198 when the apparatus is in a clamped position.

A central portion of anvil half-section 12 includes a pair of cylindrical lateral support members 172. During assembly of anvil half-section 12 and cartridge receiving half-section 14, lateral support members 172 are supported in U-shaped recesses 174 defined in a central portion 173 of cartridge receiving half-section 14 (FIG. 28). A distal wall 173 a of central portion 173 defines a tissue stop (FIG. 3). Lateral support members 172 are also positioned to be received in cutouts 176 formed on spaced flange portions 178 of clamping lever 16 when the clamping lever 16 is moved to the clamped position (FIG. 2B). Proximal handle portion 12 a is ergonomically formed and includes a thumb-engaging abutment 180 and a gripping portion 182. A proximal end of handle portion 12 a includes a downwardly extending finger 184 which includes a pair of opposed teardrop shaped protrusions 186 which will be discussed in further detail below. Alternately, protrusions 186 may assume a variety of configurations.

Cartridge receiving half-section 14 includes spaced centrally disposed U-shaped recesses 174 positioned to support lateral support members 172 of anvil half-section 12. The proximal end of cartridge receiving half-section 14 includes a pair of vertical support members 188. Each vertical support member 188 includes an elongated vertical slot 188 a having a rounded bottom surface. Vertical slots 188 a are dimensioned to receive protrusions 186 formed on finger 184 of anvil half-section 12 (FIG. 21) when the anvil half-section 12 is supported on the cartridge receiving half-section 14 during assembly. By positioning protrusion 186 within the vertical slots 188 a, anvil half-section 12 can be pivoted in a scissor-like manner with respect to the cartridge receiving half-section 14 between open and closed positions. In one embodiment, protrusions 186 have a teardrop profile. At least one sidewall of cartridge receiving half-section 14 includes a depression 189 (see FIG. 3) which will be discussed in further detail below.

Clamping lever 16 also includes a handle portion 190 including a grip 190 a and a thumb engaging abutment 192. As discussed above, a pair of spaced flange portions 178 are supported on the distal end of clamping lever 16. Each flange portion 178 defines a cutout 176 dimensioned to receive a respective lateral support member 172 of anvil half-section 12 when stapler 10 is moved towards clamped position (FIG. 2B). The distal end of clamping lever 16 also defines a pair of openings 194 which are dimensioned to receive a pivot member 187. Pivot member 187 is dimensioned to extend through openings 195 in cartridge receiving half-section 14 and openings 194 in clamp lever 16 to pivotally secure clamp lever 16 to cartridge receiving half-section 14.

As shown in FIG. 3A, an inner wall of clamping lever 16 includes a protrusion 201. Protrusion 201 is positioned within depression 189 (FIG. 2A) formed in the sidewall of cartridge receiving half-section 14 to releasably retain clamp lever 16 in the unclamped position or open position (FIG. 2A).

In order to load firing assembly 20 into proximal portion 24 b of channel member 22, the stationary housing 26 of firing assembly 20 is slid into the channel member 22 through the proximal end of channel member 22 until pivot members 29 are received in recesses 30 formed in the proximal end of channel member 22. After firing assembly 20 is loaded, the SULU 18 can be loaded into distal portion 24 a in the manner discussed above.

Referring to FIGS. 2 and 2B, after SULU 18 and firing assembly 20 are loaded into channel member 22, anvil section 12 can be assembled to cartridge receiving half-section 14. To attach anvil half-section 12 to cartridge receiving half-section 14, protrusions 186 of fingers 184 are positioned in vertical slots 188 a of vertical support member 188 of cartridge receiving half-section 14. Thereafter, anvil half-section 12 is rotated towards cartridge receiving half-section 14 to position lateral supports members 172 in U-shaped recesses 174.

In order to position surgical stapler 10 in the clamped position, clamping lever 16 is rotated in a counter-clockwise direction from the position shown in FIG. 2A. As clamping lever 16 is rotated, lateral support members 172 are received in cutouts 176 (FIG. 2) of flange portions 178 and cammed towards cartridge receiving half-section 14. As shown in FIG. 3, a spring member 200 is secured to an inner surface of clamping lever 16, such as by welding, at a position to engage cartridge receiving portion 14 to urge clamping lever 16 to the non-clamped position shown in FIG. 2A. In the clamped position shown in FIG. 1, the staple deforming portion 198 is positioned in close approximation with the top surface of SULU 18.

Referring to FIGS. 3, 3A and 12, as discussed above, a pivotal locking member 206 is pivotally supported on the proximal end of stationary housing 26 of firing assembly 20. Pivotal locking member 206 includes pivot members 29 which extend through openings 28 defined in stationary housing 26. A finger engagement member 212 is positioned on one end of locking member 206 and a latch portion 210 is positioned on the other end of locking member 206. Latch portion 206 includes a hook member 210 a. A biasing member 214 is positioned about a pivot member 29 to urge latch portion 210 inwardly towards stationary housing 26 of firing assembly 20. When locking member 206 is secured on firing assembly 26, latch portion 210 extends downwardly through an opening 216 in a proximal end of stationary housing 26 to a position below a bottom surface of channel member 22 (FIG. 20). As discussed above, the ends of pivot members 29 are received in cutouts 30 formed in the proximal end of cartridge receiving half-section 14 to releasably secure firing assembly 20 within proximal channel portion 24 b of channel member 22 (FIG. 21). Cutouts 30 are partially defined by downturned fingers 220 to retain firing assembly 26 within channel member 22 (FIG. 3).

Referring to FIG. 3A, a proximal end of clamping lever 16 includes an engagement member, e.g., cylindrical post 218, which is positioned to be engaged by hook member 210 a of latch portion 210 when the clamp lever 16 is moved to the clamped position (FIG. 27). Although a post is illustrated, other engagement member configurations are envisioned. As can be seen by viewing FIG. 27, as clamping lever 16 is moved towards the clamped position, an angled face 222 of latch portion 210 engages post 218. This engagement causes locking member 206 to pivot about pivot members 29 such that hook member 210 a of latch portion 210 passes by and then snaps into engagement with post 218. To release latch portion 210 from post 218, engagement member 212 of locking member 206 is depressed to pivot latch portion 210 out of engagement with post 218. When this occurs, spring member 200 urges clamping lever 16 to the unclamped position.

Referring to FIGS. 3, 12, 19 and 26, as discussed above, guide block 48 is pivotally supported in stationary housing 26 of firing assembly 20. Guide block 48 includes a distally extending nose portion 220 (FIGS. 12 and 26) which rests beneath SULU 18 when SULU 18 is supported in channel member 22. The internal surface of guide block 48 includes locking surfaces 222 (FIG. 19) which are received in notches 49 and 51 of knife actuating bar 44 when the stapler 10 is in an unclamped position. When the SULU 18 is positioned in the channel member 22, prior to moving clamp lever 16 to the clamped position, SULU 18 is positioned atop nose portion 220 and is not fully seated in the channel member 22, as discussed above. When the stapler 10 is moved to the clamped position, locating fingers 170 (FIG. 3) engage a top surface of body 120 of SULU 18 to fully seat SULU 18 in channel member 22. As discussed above, locating fingers 170 are received in grooves in SULU 18 to properly position SULU 18 in relation to anvil portion 12 b. As SULU 18 is fully seated in channel member 22, SULU 18 presses downwardly on nose portion 220 of guide block 48 to pivot guide block 48 about protrusions 72. When guide block 48 pivots, locking surfaces 222 move from notches 49 and 51 to unlock knife actuating bar 44 (FIG. 26). This configuration prevents movement of the knife actuating bar 44 in relation to guide block 48 prior to clamping to ensure that the knife actuating bar 44 and SULU knife 40 remain properly positioned for operational engagement prior to use.

Referring to FIGS. 24-28, when stapler 10 is in the clamped, unfired position, slide block 52 of firing assembly 20 is in the retracted position at the proximal end of channel member 22 and stationary housing 26. See FIG. 27. In this position, pedal 54 is positioned in cutout 55 of channel member 22 and pin 88 of pedal 54 is positioned in arcuate recess 94 of firing lever 50 beneath stop recesses 94 a. As such, firing lever 50 can be pivoted to facilitate actuation of stapler 10 from either side of the stapler 10. In addition, in this position of slide block 52, finger 108 of knife actuating bar 44 is positioned adjacent the distal wall of recess 110 of slide block 52. Latch portion 210 of locking member 206 is also engaged with post 218 to retain clamping lever 16 in the clamped position.

Referring to FIG. 26, when slide block 52 is in the retracted position, knife 40 and cam surfaces 114 b of cam bar 46 are positioned in the proximal end of SULU 18 and, proximal hook 156 of safety lockout 128 is positioned in engagement with engagement member 158 of knife 40 to retain safety lockout 128 in the locked orientation. In addition, downturned hook portion 40 b of knife 40 is engaged with upturned hook portion 106 of knife actuating bar 44 to connect firing assembly 20 to knife 40 of SULU 18.

Referring to FIGS. 29-32, when the firing lever 50 is advanced distally in the direction indicated by arrow “A” in FIG. 29, slide block 52 is moved distally within stationary housing 26 of firing assembly 20 to effect corresponding movement of cam bar 46 and delayed movement of knife actuating bar 44. As discussed above, the delayed movement of the knife actuating bar 44 is equal to the length of recess 110 of slide block 52 and results from movement of finger 108 of knife actuating bar 44 within recess 110 of slide block 52. Movement of knife actuating bar 44 with slide block 52 begins when finger 108 abuts the proximal wall 112 of recess 110. As cam bar 46 is moved distally through stationary housing 26 of firing assembly 20, cam surfaces 114 b on sidewalls 114 of cam bar 46 are advanced through SULU 18 to sequentially engage pushers 122 to eject staples 126 from slots 130 of body 120. Concurrently, since the distal end of knife actuating bar 44 is engaged with knife 40, knife 40, after the preset delay, is advanced through SULU 18 to incise tissue between the staple lines.

As shown in phantom in FIG. 32, when slide block 52 moves distally within stationary housing 26, pedal 54 rides up over channel member 22 and moves along inner surface of stationary housing 26 of firing assembly 20. When this occurs, pin 88 of pedal 54 moves into a stop recess 94 a to prevent further pivotal movement of firing lever 50.

Referring to FIGS. 31 and 32, when knife 40 is moved distally within SULU 18, engagement member 158 of knife 40 is disengaged with proximal hook 156 of safety lockout 128.

Referring to FIGS. 33 and 34, when the firing lever 50 is returned to its proximal-most position to retract cam bar 46 and knife 40, and the locking member 206 is depressed to disengage latch portion 210 from post 218, spring 200 urges clamping lever 16 to its unclamped position to allow stapler 10 to move to the open position. In the open position, anvil half-section 12 is spaced from cartridge receiving half-section 14 and spring 152 (FIG. 17) pivots safety lockout 128 in the direction indicated by arrow B in FIG. 34 about pivot member 150 to its unlocked position such that safety lockout 128 projects upwardly from SULU 18. In the unlocked position, safety lockout 128 prevents movement of the stapler 10 back to the clamped position. In order to reuse stapler 10, used SULU 18 must be replaced with a new SULU 18.

During a surgical procedure, SULU 18 can be replaced multiple times to facilitate multiple uses of stapler 10 on a single patient. Since each SULU 18 is provided with a fresh knife 40, tearing of tissue is minimized. After the surgical procedure, the used SULU(S) 18 and the firing assembly 20 can be removed from the channel member 22 and disposed of in an appropriate manner. The anvil half-section 12, cartridge receiving half-section 14 and clamping lever 16 can now be sterilized, such as by autoclaving, and reused with a sterilized SULU 18 and firing assembly 20 in the manner discussed above. Because the locking member 206 forms part of the firing assembly 20 and is disposable, fewer areas remain on the reusable components for tissue and fluids to become trapped. As such, the reusable components of the apparatus can be more easily sterilized.

In the surgical stapler described above, the SULU 18 and the firing assembly 20 are independently secured to and independently removed from the channel member 22 of the cartridge receiving half-section 14. In alternative embodiments illustrated in FIGS. 35-37B, the SULU 18 and the firing assembly 20 are configured to form a single disposable unit, and the cartridge receiving half-section is configured to receive the single disposable unit. In particular, the stationary housing of the firing assembly supports both the SULU and the firing components of the surgical stapler 10, e.g., knife actuating bar, cam bar, guide block, and slide block shown in FIGS. 8-12. When the stationary housing is inserted into the channel member 22 of the cartridge receiving half-section, the SULU and the firing components are concurrently mounted to the cartridge receiving half-section. The stationary housing includes a lockout structure which prevents insertion of the stationary housing into the cartridge receiving half-section if the SULU is not first mounted within the stationary housing. Thus, the SULU must be inserted into the stationary housing before inserting the stationary housing into the cartridge receiving half-section. Specific embodiments of the stationary housing are discussed below.

FIGS. 35-35A illustrate an alternate embodiment of the stationary housing, designated by reference numeral 526, associated with the firing assembly 520. The stationary housing 526 can define a length substantially similar to that of the cartridge receiving half-section 14 (FIG. 3). The stationary housing 526 as a whole is configured to be releasably received within the channel member 22 of the cartridge receiving half-section 14 of FIG. 4. The stationary housing 526 includes a proximal portion 530, a distal portion 532 and a center portion 540 therebetween. The stationary housing 526 further defines a channel 566 therein, defined between the sidewalls of stationary housing 526.

The proximal portion 530 of the stationary housing 526 is configured to support the firing components of the surgical stapler 10 as shown in FIGS. 8-12, in the same manner as stationary housing 26, such firing components including the knife actuating bar, cam bar, guide block, and slide block (not shown in FIG. 35).

The distal portion 532 and the center portion 540 of the stationary housing 526 together are of a length substantially similar to that of the SULU 18 shown in FIG. 3. The distal portion 532 and the center portion 540 together are configured to releasably receive the SULU 18 of FIG. 3.

The center portion 540 of the stationary housing 526 has a pair of sidewalls 542 that define cutouts 546 configured to receive protrusions 65 shown in FIGS. 9B-9C of the cartridge receiving half-section. The distal portion 532 has a U-shaped frame 560 including a bottom surface 562 and a pair of sidewalls 564.

The distal portion 532 includes at least one flexible member 533 which is movable within at least one cutout 536 defined in the U-shaped frame 560. As shown in FIGS. 35-35A, the distal portion 532 may include a pair of flexible members 533 formed in sidewall 564 movable within cutouts 536 that are preferably symmetrically defined in the U-shaped frame 560. Each cutout 536 has an L-shaped configuration, including a longitudinal opening 537 defined on the sidewall 564 of the U-shaped frame 560 and a lateral opening 538 defined on the bottom surface 562 of the U-shaped frame 560. Each flexible member 533 has a flexible and resilient nature, and includes a first portion 534 hingedly attached to an upper end of its associated sidewall 564. The first portion 534 extends inwardly from the upper end of its associated sidewall 564, and protrudes downwardly (in the orientation of FIG. 35), gradually away from the longitudinal opening 537. The downward inclination of the first portion 534 facilitates insertion of the SULU 18 in a downward direction into the stationary housing 526. Each flexible member 533 also includes a second portion 535 extending from the first portion 534 in a substantially parallel relation with its associated sidewall 564, and having a protrusion 539 protruding downwardly beyond the lateral opening 538 beyond the bottom surface 562. Due to the hinge connection between each flexible member 533 and its associated sidewall 564, the first portion 534 of each flexible member 533 is pivotable with respect to the associated sidewall 564, and the second portion 535 is movable across the lateral opening 538. The flexible members 533 are preferably integrally formed with sidewall 564, however, alternatively, they could be a separate component attached to the sidewall 564.

The flexible members 533 define a first position as shown in FIG. 35A where each flexible member 533 is misaligned with respect to its associated sidewall 564. In this position, the second portion 535 of the flexible member 533 is spaced inwardly away from the associated sidewall 564. The flexible members 533 also define a second position in which each flexible member 533 is substantially aligned with respect to its associated sidewall 564. In the second position, each first portion 534 moves within the longitudinal opening 537 of its associated cutout 536, and each flexible member 533 as a whole resides in substantially the same plane as its associated sidewall 564. The flexible members 533 normally assume their first position in the absence of any external force or pressure. Application of an outward force, such as by inserting the SULU 18 into the stationary housing 526, flexes the flexible members 533 outwardly (in a direction away from the longitudinal axis of stationary housing 526) due to the flexible nature of the flexible members 533, moving the flexible members 533 from their first position to their second position. Upon removal of the force, e.g., removal of the SULU 18 from the stationary housing 526, the flexible members 533 resume their first position due to their resilient nature.

FIGS. 36-36A illustrate an alternate embodiment of the cartridge receiving half-section 514 for use with the stationary housing 526. The cartridge receiving half-section 514 defines an elongated channel member 522 configured to receive the stationary housing 526. Specifically, the cartridge receiving half-section 514 includes a proximal portion 524 b, a distal portion 524 a, and a center portion 573 configured to receive the proximal portion 530, the distal portion 532 and the center portion 540 of the stationary housing 526, respectively. The cartridge receiving half-section 514 includes a pair of sidewalls 527 and a bottom surface 528 that defines at least one groove or recess 570 therein.

As shown in FIGS. 36-36A, the cartridge receiving half-section 514 may define a pair of grooves 570 extending longitudinally substantially parallel to the longitudinal axis of channel member 522. Each groove 570 is of a length sufficient to accommodate the protrusion 539 of one of the flexible members 533.

When the stationary housing 526 is properly received within the cartridge receiving half-section 514, the bottom surface 562 of the stationary housing 526 is placed against the bottom surface 528 of the cartridge receiving half-section 514, and the protrusions 539 of the flexible members 533 are positioned within the grooves 570 of the cartridge receiving half-section 514.

The pair of grooves 570 is disposed immediately adjacent to the pair of sidewalls 527 of the cartridge receiving half-section 514. Due to the close proximity between the grooves 570 and the sidewalls 527, the grooves 570 receive the protrusions 539 of the flexible members 533 only when the flexible members 533 are in their second position. That is, when the flexible members 533 are in their second position, the protrusions 539 are aligned with respect to the grooves 570 and are thus insertable into the grooves 570.

On the other hand, when the flexible members 533 are in their first position, the protrusions 539 are misaligned with respect to the grooves 570. In this situation, the protrusions 539 abut the bottom surface 528 of the cartridge receiving half-section 514, and prevent full insertion of the stationary housing 526 into the cartridge receiving half-section 514.

Accordingly, when the flexible members 533 are in the first position, absent a SULU, the stationary housing 526 cannot be fully and operably inserted into the cartridge receiving half-section 514. In contrast, when the flexible members 533 are in the second position, in the presence of a SULU, the stationary housing 526 can be fully and operably inserted into the cartridge receiving half-section 514.

During operation, a user first positions a SULU 18 into the center portion 540 and the distal portion 532 of the stationary housing 526. As the SULU 18 enters the stationary housing 526 in a downward direction, the SULU 18 applies an outward force to each flexible member 533, and biases the flexible members 533 from the first position to the second position. After the SULU 18 is placed within the stationary housing 526, the SULU 18, the stationary housing 526 and the firing components carried by the stationary housing 526 together form a single disposable unit. The user then mounts the single disposable unit into the cartridge receiving half-section 514 by placing the stationary housing 526 into the channel member 522 of the cartridge receiving half-section 514.

If the user attempts to mount the stationary housing 526 into the cartridge receiving half-section 514 without first inserting the SULU 18 into the stationary housing 526, the flexible members 533 of the stationary housing 526 are in their first position as described above, thereby preventing the stationary housing 526 from being mounted within the cartridge receiving half-section 514.

FIGS. 37-37B illustrate another alternate embodiment of the stationary housing, designated by reference numeral 626. In this embodiment, the distal portion 632 of the stationary housing 626 defines at least one cutout 674 that allows at least one flexible member 670 with a flexible, resilient nature to pivot or move within the at least one cutout 674. In one instance, the distal portion 632 may include a pair of cutouts 674 at the upper end of each sidewall 664 forming a pair of flexible members 670. The cutouts 674 may be symmetrically arranged on the sidewalls 664. Alternatively, the flexible members 670 can be separate components attached to sidewalls 664.

Each flexible member 670 is extended from an associated sidewall 664 and positioned about the cutout 674 defined in the associated sidewall 664. Each flexible member 670 has a first portion 672 hingedly attached to its associated sidewall 664 at the lower edge 676 of the cutout 674. The first portion 672 is of a height “H” identical or substantially similar to that of the cutout 674. Additionally, each flexible member 670 includes a second portion 678 exhibiting a hook, U-shaped, or concave configuration with a recess 679 defined therein, and facing in opposing radial directions. Each recess 679 faces a generally downward direction, as viewed in the orientation of FIG. 37. Each recess 679 is configured to receive a top edge 628 of a sidewall 627 of the cartridge receiving half-section 614 therein.

Due to the hinge connection between each flexible member 670 and its associated sidewall 664, each flexible member 670 is pivotable with respect to its associated wall 664. Specifically, the flexible members 670 have a first position, as illustrated in FIG. 37A, in which the first portion 672 of each flexible member 670 is misaligned with respect to its associated sidewall 664. In this first position, the pair of first portions 672 inclines inwardly towards each other. When the flexible members 670 are in the first position, each recess 679 is misaligned with respect to a corresponding top edge 628 of a sidewall 627 of the cartridge receiving half-section 614. As shown in FIG. 37A, if the user attempts to mount the stationary housing 626 into the cartridge receiving half-section 614 while the flexible members 670 are in the first position, the second portions 678 of the flexible members 670 abut top edges 628 of the sidewalls 627 of the cartridge receiving half-section 614 and prevent full insertion of the stationary housing 626 into the cartridge receiving half-section 614.

Additionally, the flexible members 670 define a second position, as illustrated in FIG. 37B, in which each first portion 672 is biased into its associated cutout 674 in alignment with its associated sidewall 664. In the second position, the recesses 679 defined by second portions 678 are aligned with respect to the corresponding top edges 628 of the cartridge receiving half-section 614, and are positioned to readily receive the top edges 628 therein.

The flexible members 670 normally assume their first position in the absence of any force or pressure applied thereto. However, application of external force to the flexible members 670, such as by inserting the SULU 618 (similar to SULU 18) into the stationary housing 626, urges each flexible member 670 from the first position to the second position. Due to the resilient nature of the flexible members 670, removal of the SULU 618 from the stationary housing 626 returns the flexible members 670 from the second position to the first position.

Accordingly, when the flexible members 670 are in the second position, the stationary housing 626 can be fully and operably inserted into the cartridge receiving half-section 614. By contrast, when the flexible members 670 are in the first position, the stationary housing 626 cannot be fully inserted into the cartridge receiving half-section 614.

During operation, a user first positions a SULU (e.g. SULU 618, 18) into the stationary housing 626, moving the flexible members 670 from their first position to their second position, such that the stationary housing 626 can be readily received by the cartridge receiving half-section 614. After the SULU 618 is fully inserted into the stationary housing 626, the SULU 618, the stationary housing 626 and the firing components carried by the stationary housing 626 together form a single disposable unit. The user then mounts the single disposable unit into the cartridge receiving half-section 614 by placing the stationary housing 626 into the channel member 622 of the cartridge receiving half-section 614.

If the user attempts to mount the stationary housing 626 into the cartridge receiving half-section 614 without first inserting the SULU 618 into the stationary housing 626, the flexible members 670 of the stationary housing 626 will abut the top edges 628 of sidewalls 627 of the cartridge receiving half-section 614 to prevent entry of the stationary housing 626 into the cartridge receiving half-section 614.

Flexible members 533 illustrated in FIGS. 35-35A, and flexible members 670 illustrated in FIGS. 37-37B, are both exemplary embodiments of the lockout structure, which can be used to prevent insertion of the stationary housing into the cartridge receiving half-section if the SULU is not first mounted within the stationary housing. Thus, the SULU and pusher assembly (e.g. the stationary housing) must be formed together (together forming the firing assembly) prior to insertion into the cartridge receiving half section of the apparatus.

It will be understood that various modifications may be made to the embodiments of the surgical fastener applying apparatus disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure. 

1-20. (canceled)
 21. A disposable firing assembly for use with a surgical fastener applying apparatus, the disposable firing assembly comprising a single use loading unit and a pusher assembly, the disposable firing assembly being dimensioned to be releasably received within a cartridge receiving half-section of the fastener applying apparatus, the single use loading unit being releasably mountable to the pusher assembly, wherein the disposable firing assembly includes a lockout member that is movable from a first blocking position preventing operable insertion of the disposable firing assembly into the fastener applying apparatus to a second unblocking position to enable full operable insertion of the firing assembly into the fastener applying apparatus.
 22. The disposable firing assembly according to claim 21, wherein the lockout member is biased to the first position and the single use loading unit applies a force to the lockout member when the single use loading unit is mounted to the pusher assembly to move the blocking member to the second position.
 23. The disposable firing assembly according to claim 21, wherein the lockout member includes a protrusion positioned and dimensioned to be received within a groove in the fastener applying apparatus when the lockout member is in the second position, the protrusion being misaligned with respect to the groove in the first position of the lockout member.
 24. The disposable firing assembly according to claim 21, wherein the lockout member defines a recess, the recess configured to receive a top edge of a sidewall of a cartridge receiving half-section of the fastener applying apparatus when the lockout member is in the second position, the lockout member configured to abut the top edge of the sidewall when the lockout member is in the first position.
 25. The disposable firing assembly of claim 21, further including a stationary housing, the stationary housing defining a channel that receives the single use loading unit.
 26. The disposable firing assembly of claim 25, wherein stationary housing includes a sidewall and the lockout member includes at least one flexible member formed on the sidewall.
 27. The disposable firing assembly of claim 26, wherein the at least one flexible member includes a pair of flexible members.
 28. The disposable firing assembly of claim 26, wherein the at least one flexible member is received within a cutout in the sidewall of the stationary housing.
 29. The disposable firing assembly of claim 28, wherein the at least one flexible member is formed from a resilient material.
 30. The disposable firing assembly of claim 29, wherein in an unbiased state, the at least one flexible member is in the first blocking position.
 31. The disposable firing assembly of claim 30, wherein in the unbiased state, the at least one flexible member extends into the channel of the stationary housing.
 32. The disposable firing assembly of claim 31, wherein in the second unblocking position, the at least one flexible member is biased into alignment with the sidewall of the stationary housing.
 33. The disposable firing assembly of claim 26, wherein the at least one flexible member extends below a bottom wall of the stationary housing.
 34. The disposable firing assembly of claim 26, wherein the at least one flexible member is hingedly connected to the sidewall of the stationary housing.
 35. The disposable firing assembly of claim 26, wherein the at least one flexible member includes a hook that extends above the sidewall of the stationary housing.
 36. The disposable firing assembly of claim 35, wherein the at least one flexible member includes a pair of flexible members. 